Get one of those 2 or 3 gallon garden sprayers that you pump up with air. Rig a hose for your fitting to the gun and you're set to go.
Had one setup for service calls.
GREAT suggestion! I have several of the 1 gallon versions - 1 with Merc green lube for the outdrives, another with Pennzoil synchromesh for the car transmissions, and another with mobile one ls 80-90 for the car differential. FAR easier than any other way to do this that I know of...
Ayuh,..... I put together 1 usin' a 1.5 gallon Chapin steel tank sprayer...
I cut the hose off, at 'bout 1.5', plumbed in a ball valve, 'n a Metal screw-in tip, salvaged from an ole plastic pump-bottle style, from years ago...
Got a piece of clear tubin' 'tween the ball vale, 'n tip,...
'n a 3/8"- 16 screw on cap for it...